[....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[ 16.021588] random: sshd: uninitialized urandom read (32 bytes read) [?25l[?1c7[ ok 8[?25h[?0c. [ 16.728515] random: sshd: uninitialized urandom read (32 bytes read) [ 16.984644] random: sshd: uninitialized urandom read (32 bytes read) Debian GNU/Linux 7 syzkaller ttyS0 syzkaller login: [ 17.772854] random: sshd: uninitialized urandom read (32 bytes read) [ 17.913870] random: sshd: uninitialized urandom read (32 bytes read) Warning: Permanently added '10.128.0.5' (ECDSA) to the list of known hosts. [ 23.442189] random: sshd: uninitialized urandom read (32 bytes read) executing program executing program [ 23.655603] BUG: unable to handle kernel NULL pointer dereference at 0000000000000080 [ 23.663859] IP: [] l2tp_session_free+0x11c/0x200 [ 23.670296] PGD 1c4899067 [ 23.672989] PUD 1c5896067 PMD 0 [ 23.676524] [ 23.678176] Oops: 0002 [#1] PREEMPT SMP KASAN [ 23.682657] Dumping ftrace buffer: [ 23.686174] (ftrace buffer empty) [ 23.689858] Modules linked in: [ 23.693163] CPU: 0 PID: 3777 Comm: syz-executor873 Not tainted 4.9.120-gf85543b #76 [ 23.700947] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 23.710282] task: ffff8801bb529800 task.stack: ffff8801b9c38000 [ 23.716314] RIP: 0010:[] [] l2tp_session_free+0x11c/0x200 [ 23.725174] RSP: 0018:ffff8801b9c3fca0 EFLAGS: 00010246 [ 23.730603] RAX: dffffc0000000000 RBX: ffff8801ba0d8f00 RCX: 0000000000000000 [ 23.737854] RDX: 1ffff10039388cd0 RSI: ffffffff836c29a1 RDI: ffff8801c9c46680 [ 23.745112] RBP: ffff8801b9c3fcc0 R08: ffff8801bb52a0e8 R09: 0000000000000000 [ 23.752369] R10: 0000000000000000 R11: 0000000000000000 R12: ffff8801c9c46500 [ 23.759621] R13: ffff8801ba0d8f08 R14: 0000000000000000 R15: ffffffff83018be0 [ 23.766885] FS: 0000000001789880(0000) GS:ffff8801db200000(0000) knlGS:0000000000000000 [ 23.775109] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 23.780982] CR2: 0000000000000080 CR3: 00000001c5bc5000 CR4: 00000000001606f0 [ 23.788234] Stack: [ 23.790364] ffff8801bbe71100 ffff8801ba0d8f00 ffff8801bbe714d0 ffff8801bbe713d8 [ 23.798368] ffff8801b9c3fce8 ffffffff836ca2b2 ffff8801bbe71540 ffff8801bbe71100 [ 23.806369] ffffffff836ca1e0 ffff8801b9c3fd20 ffffffff830260f5 ffff8801bbe71540 [ 23.814365] Call Trace: [ 23.816941] [] pppol2tp_session_destruct+0xd2/0x110 [ 23.823613] [] ? pppol2tp_seq_start+0x4e0/0x4e0 [ 23.829914] [] __sk_destruct+0x55/0x590 [ 23.835521] [] ? sock_release+0x1c0/0x1c0 [ 23.841322] [] sk_destruct+0x63/0x80 [ 23.846671] [] __sk_free+0x4f/0x220 [ 23.851943] [] sk_free+0x2b/0x40 [ 23.856944] [] pppol2tp_release+0x239/0x2e0 [ 23.862897] [] sock_release+0x96/0x1c0 [ 23.868417] [] sock_close+0x16/0x20 [ 23.873674] [] __fput+0x263/0x700 [ 23.878772] [] ____fput+0x15/0x20 [ 23.883866] [] task_work_run+0x10c/0x180 [ 23.889583] [] exit_to_usermode_loop+0xfc/0x120 [ 23.895901] [] do_syscall_64+0x364/0x490 [ 23.901599] [] entry_SYSCALL_64_after_swapgs+0x5d/0xdb [ 23.908497] Code: 49 8d bc 24 80 01 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 80 3c 02 00 0f 85 c6 00 00 00 4d 8b b4 24 80 01 00 00 41 ff 8e 80 00 00 00 74 69 e8 15 de c9 fd 4c 89 ea 48 b8 00 [ 23.935780] RIP [] l2tp_session_free+0x11c/0x200 [ 23.942319] RSP [ 23.945920] CR2: 0000000000000080 [ 23.949971] ---[ end trace af49d8dd142473ee ]--- [ 23.954745] Kernel panic - not syncing: Fatal exception [ 23.960395] Dumping ftrace buffer: [ 23.963934] (ftrace buffer empty) [ 23.967621] Kernel Offset: disabled [ 23.971222] Rebooting in 86400 seconds..